diff --git a/rattail_fabric/postfix.py b/rattail_fabric/postfix.py
index a684617..cce6215 100644
--- a/rattail_fabric/postfix.py
+++ b/rattail_fabric/postfix.py
@@ -59,14 +59,11 @@ def restart():
     sudo('service postfix restart')
 
 
-def set_config(setting, value, path='/etc/postfix/main.cf'):
+def set_config(setting, value):
     """
     Configure the given setting with the given value.
     """
-    # replace setting if already exists; then add in case it didn't
-    entry = '{} = {}'.format(setting, value)
-    sed(path, r'^{} = .*$'.format(setting), entry, use_sudo=True)
-    append(path, entry, use_sudo=True)
+    sudo("postconf -e '{}={}'".format(setting, value))
 
 
 def set_myhostname(hostname):